Electromagnetic pickup devices are used in conjunction with stringed musical instruments such as electric guitars and basses to convert the vibrations resulting from the movement or “picking” of the strings into electrical signals, for subsequent transmission to amplification devices to produce a desired sound. The pickup is generally positioned under the strings of the instrument on the base surface and the signal transmitted by an electromagnetic pickup is dependent upon the motions of each string.
The most essential components of a dual coil pickup are a permanent magnet and two coils of wire. Generally, two oppositely polarized magnets will be used although in some embodiments, only a single bipolar magnet is incorporated into the embodiments. The magnets generate a magnetic field that passes through the pickup coils and also extends into a space occupied by at least one string of the instrument. Vibration of the string changes the reluctance of the magnetic path and creates disturbances in the magnetic field proportional to the string vibration. The changing magnetic field in the pickup coils in turn induces an electrical signal in the coils. From the output of the pickup, a circuit connection is made to an amplifier.
There are several types of pickups with varying coil configurations known in the art. One type of electromagnetic pickup device is a dual coil pickup or a humbucking pickup. In a humbucking pickup, two coils are associated or connected in a manner so as to reduce hum.
As a rule, a central design problem of any pickup is that of obtaining both a faithful signal and a good signal to noise ratio. It is well known that the pickup coils, in addition to their desired function of picking up string vibrations, also tend to pick up electrical noise and interference signals from various extraneous sources. Also, because of the impedance associated with common dual coil pickups, frequency response may be limited. Therefore, there is significant value in a pickup that has improved noise rejection of radiated frequencies from extraneous sources and extending the frequency response while still maintaining response to desirable string vibrations.